long yearsUntil(Symmetry010Date end) {
        long startYear = this.prolepticYear * 512L + this.getDayOfYear();
        long endYear = end.prolepticYear * 512L + end.getDayOfYear();
        return (endYear - startYear) / 512L;
    }
long yearsUntil ( Symmetry010Date end ) { long startYear = this . prolepticYear * 512L + this . getDayOfYear ( ) ; long endYear = end . prolepticYear * 512L + end . getDayOfYear ( ) ; return ( endYear - startYear ) / 512L ; }
Get the number of years from this date to the given day.

@param end The end date.
@return The number of years from this date to the given day.