/**
 * Display pagination information in the format "X - Y of Z".
 * 
 * @param object $wp_query Optionally generate string from custom query, defaults to main.
 */
function wpse_106121_posts_count( $wp_query = null ) {
    if ( ! $wp_query )
        global $wp_query;

    $posts = min( ( int ) $wp_query->get( \'posts_per_page\' ), $wp_query->found_posts );
    $paged = max( ( int ) $wp_query->get( \'paged\' ), 1 );
    $count = ( $paged - 1 ) * $posts;

    printf(
        \'%d - %d of %d\',
        $count + 1,
        $count + $wp_query->post_count,
        $wp_query->found_posts
    );
}

<?php wpse_106121_posts_count() ?>