I've just happened to come across some biomes, and I want to know how rare it is

The rarity of the biomes you have found are listed below:

1. Ice Spikes: 0.11%
2. Shattered Savanna: 0.1%
3. Modified Wooded Badlands Plateau: 0.02%
4. Desert Lakes: 0.17%
5. Gravelly Mountains: 0.43%
6. Snowy Tundra: 1.13%
7. Snowy Taiga Hills: 0.13%

These results were created by generating 12,000 worlds in Minecraft 1.13.1. These results may vary slightly, but these are the approximate percentages. I found this information from here.

The top rarest biomes go in this order (1: rarest, 11: rare).

1. Modified Jungle Edge.
2. Modified Badlands Plateau
3. Snowy Taiga Mountains
4. Mushroom Fields and Mushroom Shore.
5. Bamboo Jungle and Bamboo hills
6. Eroded Badlands
7. Giant Tree Tiaga and all variants.
8. Gravelly Hills and Gravelly Mountains
9. Ice Spikes
10. Shattered Savanna & Shattered Savanna Plateau.
11. Swamp Hills

Source