A San Francisco Chronicle analysis of campaign finance data filed with the secretary of state shows the two sports betting ballot measures have attracted the most money. Dialysis companies have poured more than $80 million into the campaign to oppose Proposition 29, a measure that would increase regulations on dialysis clinics, making it the next most expensive ballot measure this year. In contrast, opponents of Proposition 1, which would enshrine abortion rights into the California Constitution, have raised a paltry $297,000, compared with supporters’ $16 million. No groups are spending to oppose Proposition 28, which would increase how much California spends on arts and music education in public schools.