Convert annual counts into monthly counts using photo-user-days.
yearsToMonths(visitation_years, pud)
Arguments
visitation_years: A numeric vector with annual visitation counts. If not available, NA should be entered.
pud: A numeric vector for the monthly photo-user-days corresponding to visitation_years. As such, the length of pud needs to be exactly 12 times as long as visitation_counts.
Returns
A numeric vector with estimated monthly visitation counts based on the annual counts and monthly photo-user-days.