By Richard Horgan Los Angeles (Knewz) — One in four Americans say they have experienced three or more power outages in the last year, and many are concerned about the growing number of outages, a survey found. According to a new poll of 2,000 Americans by portable energy equipment manufacturer Goal Zero, just 15 percent currently have a backup for electrical power. At press time, there are still more than 460,000 households in Puerto Rico without power in the wake of Hurricane Fiona. While power outages across America average out to two a year, 26 percent of respondents told Goal Zero they hav…