Time series from the explorer's statistics service. Without "chart", lists the available charts with id, section, description, units and resolutions: accounts (accountsGrowth, activeAccounts, newAccounts), transactions (newTxns, txnsGrowth, txnsFee, averageTxnFee, txnsSuccessRate), blocks (newBlocks, averageBlockSize, averageBlockRewards), LAX transfers (newNativeCoinTransfers), gas (averageGasPrice, averageGasLimit, averageGasUsed, gasUsedGrowth, networkUtilization) and contracts (newContracts, contractsGrowth, newVerifiedContracts, verifiedContractsGrowth). With "chart", returns its points (date, value) at "resolution" DAY (default), WEEK, MONTH or YEAR, from "from" to "to" (YYYY-MM-DD; by default the last 90 points), at most 400. Units are reported per chart (fees in LAX, gas prices in gwei); "approximate" marks a period still in progress. For the last 7 days of hashrate, difficulty, block time and node counts, use network_trends.