Sorry for the late reply. SPI is a growth fund first and foremost with it's dividend being more of a novelty for token holders that feeds a little HIVE each week.
SPI is 36 weeks into its year and as the price of holdings are always going up and down, it's hard to get a solid number. The average YTD fund value is 329,366.86 HIVE and the average dividend YTD has been 113.97 HIVE per week. This would give a APY of 3.61% based on the average value.
In general, if HIVE increases in price, the dividend APY will increase and vice versa when HIVE prices declines.
Hope that answered your question