The caption mentions there are 937 total known characters.
The pie chart says 26% of these characters are hobbits, so there are
0.26 × 937 ≈ 243.62 hobbits
so at least 243 hobbits.
If 74 of them are female, then they make up
74/243 ≈ 0.304527 ≈ 30.5%
of the total number of hobbits.
