What are the percentage rates for each promotion type? I could not find the database which has this, but I would like to know what percentage of promoted pawns ends up being a queen, rook, bishop, or knight
Here are the percentages for each promotion type according to different sources:
|Promotion type  | ChessBase | TWIC | ICCF |
--------------------------------------------
| Queen          |      96.9 | 97.3 | 96.1 |
| Rook           |       1.1 |  1.1 |  1.7 |
| Knight         |       1.8 |  1.3 |  1.7 |
| Bishop         |       0.2 |  0.3 |  0.5 |

Details:

ChessBase: Percentages from 2006 ChessBase, with 3.2 million games, obtained from Wikipedia.
TWIC: Percentages calculated using my own script from 1.4 million games published in The Week In Chess, issues 920 (Jun. 25th, 2012) to 1358 (Nov. 16th, 2020).
ICCF: Percentages calculated using my own script from 0.8 million games made available by the International Correspondence Chess Federation, from the 1970s to 2018.