(Adds details about public debt expectations) MEXICO CITY, Dec 17 (Reuters) - Mexico expects to see a decline in its public sector debt as a proportion of gross domestic product (GDP) next year as the economy recovers after suffering a deep recession, the finance ministry said on Thursday. Public sector debt is expected to fall to 52.6% of GDP in 2021 from 53.5% this year, the ministry said in its annual financing plan document. The deficit, which stood at 44.5% of GDP in 2019, was blown out this year by the impact of the coronavirus pandemic on Mexico’s economy, which is suffering its biggest contraction since the 1930s. The sharp weakening of the peso against the dollar, which has since been reversed to a large degree, was another major factor for the sharp rise in debt as a percentage of the GDP, the finance ministry said. Mexico expects to slowly lower the debt-to-GDP ratio over the next five years, eventually pulling it to 51.4% of GDP of the economy by 2025, according to the finance ministry forecasts.