Grouping with LINQ to SQL filtered

// The following groups purchases by year, then returns only those groups where
// the average purchase across the year was greater than $1000:

from p in Purchases
group p.Price by p.Date.Year into salesByYear
where salesByYear.Average (x => x) > 1000
select new
{
        Year       = salesByYear.Key,
        TotalSales = salesByYear.Count(),
        AvgSale    = salesByYear.Average(),
        TotalValue = salesByYear.Sum()
}

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