Ring Currents and Aromaticity of Monocyclic π-Electron Systems C\\r sub/6sub\\r H\\r sub/6sub\\r , B\\r sub/3sub\\r N\\r sub/3sub\\r H\\r sub/6sub\\r , B\\r sub/3sub\\r O\\r sub/3sub\\r H\\r sub/3sub\\r , C\\r sub/3sub\\r N\\r sub/3sub\\r H\\r sub/3sub\\r , C\\r sub/5sub\\r H\\r sub/5subsup-sup\\r , C\\r sub/7sub\\r H\\r sub/7subsup+sup\\r , C\\r sub/3sub\\r N\\r sub/3sub\\r F\\r sub/3sub\\r , C\\r sub/6sub\\r H\\r sub/3sub\\r F\\r sub/3sub\\r , and C\\r sub/6sub\\r F\\r sub/6sub