The Caledon Institute of Social Policy [2] has a brief research note [3] showing that taken together, Employment Insurance premiums and Canada Pension Plan contributions net of federal non-refundable tax credits have increased only modestly in real terms since 1995, and have been essentially flat since 2002.
The research note also points out that Canada's social security contributions (so-called 'payroll taxes') are quite modest when stacked up against other OECD countries. For a single worker earning an average income, Canada's social security contributions as a share of average gross earnings placed it 24th out of 32 countries, below the US and well under the OECD average.