Convertible arbitrage strategies

A solution from CFAI online practice question “Convertible arbitrage strategies have performed best when convertible issuance is high (implying a wider choice among convertible securities as well as downward price pressure and cheaper prices), general market volatility levels are moderate, and the liquidity to trade and adjust positions is sufficient.”
what does “high” mean, issuance size or price?

Number of issuances, i.e. more issuers issuing convertible bonds