Proposition 103, codified at Ins. Code § 1861.01, mandated that property and casualty insurance rates be rolled back to what level below November 8, 1987 rates?

Why this is the answer

Ins. Code § 1861.01(a), enacted by Proposition 103 in 1988, required every insurer subject to the chapter to reduce its rates for policies issued or renewed in the first year after the initiative's effective date to a level at least 20% below the rates in effect on November 8, 1987. Subsection (b) permitted an insurer to seek a variance only by proving that the rollback would result in a 'substantially confiscatory' return on equity. Litigation over the rollback continued for more than a decade, with the California Supreme Court upholding the rollback's facial constitutionality in Calfarm Insurance v. Deukmejian (1989). See Ins. Code § 1861.01.