What is the 1989–90 answer when the 2004–05 shows grp?
CREATE TABLE "competition_timeline" (
  "competition" text,
  "1970_71" text,
  "1971_72" text,
  "1972_73" text,
  "1973_74" text,
  "1974_75" text,
  "1975_76" text,
  "1976_77" text,
  "1977_78" text,
  "1978_79" text,
  "1979_80" text,
  "1980_81" text,
  "1981_82" text,
  "1982_83" text,
  "1983_84" text,
  "1984_85" text,
  "1985_86" text,
  "1986_87" text,
  "1987_88" text,
  "1988_89" text,
  "1989_90" text,
  "1990_91" text,
  "1991_92" text,
  "1992_93" text,
  "1993_94" text,
  "1994_95" text,
  "1995_96" text,
  "1996_97" text,
  "1997_98" text,
  "1998_99" text,
  "1999_00" text,
  "2000_01" text,
  "2001_02" text,
  "2002_03" text,
  "2003_04" text,
  "2004_05" text,
  "2005_06" text,
  "2006_07" text,
  "2007_08" text,
  "2008_09" text,
  "2009_10" text,
  "2010_11" text,
  "2011_12" text
);
SELECT "1989_90" FROM "competition_timeline" WHERE "2004_05"='grp';