Before revision:  We use empirical data of nation-wide interbank liabilities to show that a few liabilities carry the major fraction of the overall SR . We propose a tax on individual transactions that is proportional to their  contribution to overall SR.
After revision:  We use empirical data of nation-wide interbank liabilities to show that the marginal contribution to overall SR of liabilities for a given size varies by a factor of a thousand . We propose a tax on individual transactions that is proportional to their contribution to overall SR.