async fetch(days) {
        const siteTimezone = this._settingsCache.get('timezone');
        const totalMembers = await this.getTotalMembers();

        // perform final calculations in parallel
        const [total, totalInRange, totalOnDate, newToday] = await Promise.all([
            totalMembers,
            this.getTotalMembersInRange({days, totalMembers, siteTimezone}),
            this.getTotalMembersOnDatesInRange({days, totalMembers, siteTimezone}),
            this.getNewMembersToday({siteTimezone})
        ]);

        return {
            total,
            total_in_range: totalInRange,
            total_on_date: totalOnDate,
            new_today: newToday
        };
    }
Fetches member's signup statistics

@param {Number | String} days  - number of days to fetch of 'all-time' to get for all existing records