Wordpress: Consulta de woocommerce para obtener el importe total de todas las ventas realizadas entre dos fechas

SELECT SUM(order_total)
FROM
(
    SELECT p.ID as order_id,
    p.post_date,
    max( CASE WHEN pm.meta_key = '_order_total' and p.ID = pm.post_id THEN pm.meta_value END ) as order_total
    FROM
    wp_posts p LEFT JOIN wp_postmeta pm ON (pm.post_id = p.ID )
    LEFT JOIN wp_woocommerce_order_items oi ON (p.ID = oi.order_id)
    WHERE
        p.post_type = 'shop_order' AND
        (
            p.post_status = 'wc-completed' OR
            p.post_status = 'wc-processing' OR
            p.post_status = 'wc-on-hold'
        ) AND
        p.post_date BETWEEN '2016-01-01 00:00:00' AND '2016-12-31 23:59:59'
    group by p.ID
)
AS total_orders_by_year;