Let's start with the national average percentage of adults in the USA. Below is a link and and excerpt, the first thing you need to extrapolate is what the number of eligible voters should be.
https://en.wikipedia.org/wiki/Demogr...ed_States#Ages
http://www.indexmundi.com/facts/unit...under-18#table
Voter registration[edit]
Population and registered voters
Total population[19] 9,787,747
Registered voters[34][note 1] [B]4,865,403[/B] 49.7%
Democratic[34] 2,486,479 51.1%
Republican[34] 1,048,507 21.6%
Democratic–Republican spread[34] +1,437,972 +29.5%
Independent[34] 109,055 2.2%
Green[34] 24,534 0.5%
Libertarian[34] 25,808 0.5%
Peace and Freedom[34] 24,950 0.5%
Americans Elect[34] 2,583 0.1%
Other[34] 262,180 5.4%
No party preference[34] 881,307 18.1%
Los Angeles County vote
by party in presidential elections[33]
Year_ GOP___________ DEM ____________ Others
2016 22.41% 769,743 71.76% 2,464,364 5.83% 200,201
So if you take the national average and compare it to LA county you will find the numbers are well within the expected results The average is over 75% voting age in California and La county has less than 50% registered. IB is a Pedant and a Liar. I have shown him the numbers and he still touts his bullshit as a tagline.