% Changes, 2018

Rankings show how name change popularity relative to each other; if you want to see how much names have changed in actual usage, you have to use statistics, I'm afraid. :p
Here are the names that gained the most usage last year (by % of babies):

Girls:

1. Mila, +0.12% (0.32% --> 0.44%)
2. Luna, +0.09% (0.28% --> 0.37%)
3. Nova, +0.06% (0.16% --> 0.22%)
4. Everly, +0.05% (0.19% --> 0.23%)
5. Camila, +0.04% (0.36% --> 0.4%)
6. Everleigh, +0.04% (0.04% --> 0.08%)
7. Amelia, +0.04% (0.63% --> 0.67%)
8. Emersyn, +0.03% (0.07% --> 0.1%)
9. Isla, +0.03% (0.15% --> 0.18%)
10. Amaya, +0.03% (0.09% --> 0.12%)
11. Ivy, +0.03% (0.15% --> 0.18%)
12. Emilia, +0.03% (0.19% --> 0.22%)
13. Valentina, +0.02% (0.16% --> 0.19%)
14. Arya, +0.02% (0.11% --> 0.14%)
15. Willow, +0.02% (0.19% --> 0.21%)
16. Rose, +0.02% (0.11% --> 0.13%)
17. Remi, +0.02% (0.07% --> 0.09%)
18. Lia, +0.02% (0.05% --> 0.07%)
19. Aria, +0.02% (0.38% --> 0.4%)
20. Ember, +0.02% (0.06% --> 0.08%)

So, Mila went from being given to about 1 in every 300 girls to about 1 in every 250 (which corresponds from her jump from #30 to #14). 

Boys:

1. Liam, +0.07% (0.95% --> 1.03%)
2. Theodore, +0.06% (0.3% --> 0.36%)
3. Asher, +0.05% (0.31% --> 0.35%)
4. Leo, +0.05% (0.3% --> 0.35%)
5. Hudson, +0.05% (0.29% --> 0.34%)
6. Ezra, +0.04% (0.27% --> 0.31%)
7. Gael, +0.04% (0.11% --> 0.15%)
8. Carson, +0.03% (0.24% --> 0.27%)
9. Mateo, +0.03% (0.39% --> 0.42%)
10. Luca, +0.03% (0.16% --> 0.19%)
11. Jack, +0.03% (0.43% --> 0.46%)
12. Santiago, +0.03% (0.21% --> 0.24%)
13. Milo, +0.03% (0.09% --> 0.11%)
14. Elias, +0.03% (0.25% --> 0.28%)
15. Brooks, +0.02% (0.1% --> 0.12%)
16. Oliver, +0.02% (0.67% --> 0.69%)
17. Matias, +0.02% (0.08% --> 0.1%)
18. Jasper, +0.02% (0.11% --> 0.13%)
19. Miles, +0.02% (0.18% --> 0.21%)
20. Henry, +0.02% (0.53% --> 0.55%)

Percentage gain favors more popular names, but if you want to see how the less common names are gaining in usage, percentage ratios are the easiest way:

Girls:

1. Zhavia (≈310.77x)
2. Roselyne (88.36x)
3. Aruna (6.38x)
4. Kailany (5.97x)
5. Huntleigh (5.62x)
6. Nuri (3.97x)
7. Stormi (3.48x)
8. Ainhoa (3.33x)
9. Alaiya (3x)
10. Meghan (2.58x)
11. Havana (2.54x)
12. True (2.51x)
13. Zhuri (2.26x)
14. Lua (2.22x)
15. Berklee (2.08x)
16. Dior (2.04x)
17. Stori (2x)
18. Esmae (1.96x)
19. Everleigh (1.96x)
20. Emori (1.91x)

So, Zhavia was approximately 311x more popular in 2018 than in 2017. 

Boys:

1. Jahseh (≈66.16x)
2. Atreus (20.23x)
3. Emric (9.6x)
4. Syre (4.54x)
5. Quadir (3.68x)
6. Kylian (3.16x)
7. Edrick (3.08x)
8. Lux (2.88x)
9. Edric (2.86x)
10. Braven (2.7x)
11. Dior (2.64x)
12. Kyro (2.51x)
13. Giannis (2.39x)
14. Axell (2.39x)
15. Ayven (2.33x)
16. Kairo (2.18x)
17. Cyril (2.18x)
18. Caelum (2.16x)
19. Genesis (2.13x)
20. Parth (2.1x)

Most of the these names are still pretty unheard-of, though (Atreus, the most common boys' name from these lists, was given to 159 boys in 2018).
Here are the names that gained the most usage in the Top 500:

Girls:

1. Everleigh (1.96x)
2. Aitana (1.69x)
3. Kailani (1.68x)
4. Kehlani (1.55x)
5. Kaylani (1.51x)
6. Oaklyn (1.47x)
7. Octavia (1.47x)
8. Emersyn (1.45x)
9. Emory (1.44x)
10. Antonella (1.44x)

Boys:

1. Kairo (2.18x)
2. Kashton (1.73x)
3. Elian (1.64x)
4. Luka (1.51x)
5. Gianni (1.43x)
6. Memphis (1.38x)
7. Gael (1.33x)
8. Milo (1.32x)
9. Matias (1.31x)
10. Hayes (1.3x)

Matias and Everleigh were on last year's list as well. Love to see Octavia, Antonella, Gael, & Milo. How high will they go?