Tips distribution

Hello everyone. I'm currently working as bar manager at an upscale Mexican restaurant that serves a very high volume of pretty elaborate cocktails. The bar however makes about half of the tips that the waiters make, and often times less than the bussers! Causing the bar to have a pretty high bartender turnover. With good bartenders being so much harder to find, I was tasked with fixing this issue, or at least mitigate it somewhat.

Current system:

- Waiters (5 of them) keep 61% of their tips;

- Bussers and Runner (4 People) get 22%;

- Barista/Desserts (Single person) 7%;

- Bar (Full bar with 18 seats (3 Bartenders) 10%.

Any sugestions? Should it be done based on beverage sales instead?