(Portland, OR)  --  State education figures show rises in high-school graduation rates for both Portland and Oregon during the 2015-16 school year.  Portland's four-year graduation rates rose from just under 74 percent for the class of 2015 to nearly 76 percent in 2016.  Oregon's graduation rate rose to nearly 75 percent in 2016, up from just under 74 percent in 2015.  The average U.S. graduation rate in 2015 was 83 percent.