az$week <-format(az$proper_date, format = "%W")
az$month <-format(az$proper_date, format = "%m")
az$year <-format(az$proper_date, format = "%y")

by_wk <- az %>% group_by(as.numeric(year), as.numeric(week), party) %>% summarise(sum = sum(contb_receipt_amt),
                                                                                  avg = mean(contb_receipt_amt))

ggplot(by_wk[!is.na(by_wk),],
       aes(week, sum, group=2, color=party))+
  geom_line()