The largest bucket may have been 21-29 years at 39%. However, the next largest was ages 30-39 at 31%, and considering all ages 30+ you have 49% of respondents.

The largest bucket may have been 21-29 years at 39%. However, the next largest was ages 30-39 at 31%, and considering all ages 30+ you have 49% of respondents. Assuming only people aged 30+ had 11+ years of experience, that would only account for half of them (49% to 25%). That doesn't sound implausible.