Here is a list of all types showing how many Pokemon there currently are of that type, listed in order of how many:
Water: 176 (81 are single-type, 95 are dual-type)
Normal: 153 (82 are single-type, 71 are dual-type)
Grass: 147 (47 are single-type, 100 are dual-type)
Psychic: 135 (47 are single-type, 88 are dual-type)
Flying: 134 (4 are single-type, 130 are dual-type)
Bug: 100 (25 are single-type, 75 are dual-type)
Fire: 97 (37 are single-type, 60 are dual-type)
Poison: 97 (16 are single-type, 81 are dual-type)
Dragon: 94 (13 are single-type, 81 are dual-type)
Fighting: 93 (30 are single-type, 63 are dual-type)
Dark: 90 (16 are single-type, 74 are dual-type)
Ground 90 (17 are single-type, 73 are dual-type)
Rock 88 (20 are single-type, 68 are single-type)
Electric: 87 (37 are single-type, 50 are dual-type)
Ghost: 87 (16 are single-type, 68 are dual-type)
Steel: 85 (12 are single-type, 73 are dual-type)
Fairy: 74 (21 are single-type, 53 are dual-type)
Ice: 65 (22 are single-type, 43 are dual-type)
Source: their pages on the DB
Hop I helped!
